I need help figuring out what went wrong with my 120mm Ducted fan w/120 amp ESC and 4000mah 60C HRB Lipo

[C-Schmitt]

I purchased all the stuff (below) to install in my home made wing. This bad boy was FAST (guessing about 200kph). 2nd flight I installed a gps speedometer to check the speed. I will admit, I had it wide open for quite a while. and suddenly lost all power and crashed in to the field. Batteries were hot, bullet connector on the esc melted off (I should have installed the emergency backup battery in to the bec to prevent the crash). anyway, I'm super curious where I went wrong. Is my C-Rating too low?

Here is the stuff I purchased

https://www.aliexpress.com/item/32961315647.html?spm=a2g0o.order_list.0.0.4fb81802A9EYsj

https://www.aliexpress.com/item/2025700513.html?spm=a2g0o.order_list.0.0.4fb81802A9EYsj

https://www.aliexpress.com/item/32984427462.html?spm=a2g0o.order_list.0.0.4fb81802A9EYsj

https://www.ebay.com/itm/38518979955...Bk9SR8qTvqGUYQ

[Evan D]

12s? The batteries had XT90? What did you do for a series connector? Picture? What plug on the ESC? Picture? Obviously your setup couldn’t handle the amperage.

[kallend]

Voltage 45-55v (10-12S lithium battery)


Current: 120A-140A

4000mAh pack

Really?

"Is my C-Rating too low?"

There is no agreed upon standard for C-rating, nor any defined way of measuring it. The C value can be anything the marketing department chooses to put on the pack and no-one can dispute it.

No way I'd use a 4000mAh pack in any model with a 120mm EDF.

[C-Schmitt]

12s? The batteries had XT90? What did you do for a series connector? Picture? What plug on the ESC? Picture? Obviously your setup couldn’t handle the amperage.

Sorry, I forgot to mention that. Yes, 2x 12s batteries. I soldered 2 XT90s to the ESC in series. sorry, no pics

[C-Schmitt]

Voltage 45-55v (10-12S lithium battery)


Current: 120A-140A

4000mAh pack

Really?

"Is my C-Rating too low?"

There is no agreed upon standard for C-rating, nor any defined way of measuring it. The C value can be anything the marketing department chooses to put on the pack and no-one can dispute it.

No way I'd use a 4000mAh pack in any model with a 120mm EDF.

Thanks for your criticism. I'm sorry if I seem like a dummy. what would you recommend?

[Evan D]

Assuming the solder joints made were well done the weak link to me are the batteries. A better C rated (remember that all C ratings are suspect) and higher capacity pack able to really supply a continuous 120-150A are needed. Ones that after a flight are no more than warm.

Please check that wires and connectors are also not more than ambient temp after flying.

[lmramos44]

I have a 120mm EDF in a T-33. 12s. I use a 180a esc, this gives you plenty of head room. I have had bad experiences with HRB. I have been using 75c Liperions with no problems. I use AS150 connectors on all my 12s jets. Very reliable. Bench test your fan and check to see what it is pulling at full throttle. I do not know how your wing is configured but depending on intake will affect your draw.